of its rapid
development at the base of its ovarian sheath, it is perhaps on its
passage through the oviduct that it receives, at the mother's pleasure,
the final impress that will produce, to match the cradle which it has to
fill, either a female or a male.

Thereupon the following question presents itself. Let us admit that,
when the normal conditions remain, a laying would have yielded m females
and n males. Then, if my conclusions are correct, it must be in the
mother's power, when the conditions are different, to take from the m
group and increase the n group to the same extent; it must be possible
for her laying to be represented as m-1, m-2, m-3, etc. females and by
n+1, n+2, n+3, etc. males, the sum of m+n remaining constant, but one of
the sexes being partly permuted into the other. The ultimate conclusion
even cannot be disregarded: we must admit a set of eggs represented
by m-m, or zero, females and of n+m males, one of the sexes being
completely replaced by the other. Conversely, it must be possible for
the feminine series to be augmented from the masculine series to the
extent of absorbing it entirely. It was to solve this question and some
others connected with it that I undertook, for the second time, to rear
the Three-horned Osmia in my study.

The problem on this occasion is a more delicate one; but I am
also better-equipped. My apparatus consists of two small, closed
packing-cases, with the front side of each pierced with forty holes,
in which I can insert my glass tubes and keep them in a horizontal
position. I thus obtain for the Bees the darkness and mystery which suit
their work and for myself the power of withdrawing from my hive, at any
time, any tube that I wish, with the Osmia inside, so as to carry it
to the light and follow, if need be with the aid of the lens, the
operations of the busy worker. My investigations, however frequent and
minute, in no way hinder the peaceable Bee, who remains absorbed in her
maternal duties.

I mark a plentiful number of my guests with a variety of dots on the
thorax, which enables me to follow any one Osmia from the beginning
to the end of her laying. The tubes and their respective holes are
numbered; a list, always lying open on my desk, enables me to note from
day to day, sometimes from hour to hour, what happens in each tube and
particularly the actions of the Osmiae whose backs bear distinguishing
marks. As soon as one tube is filled, I replace it by ano